The Literal Commandment
You shall not eat anything which dies of itself. You may give it to the alien who is in your town, so that he may eat it, or you may sell it to a foreigner, for you are a holy people to the LORD your God. You shall not boil a young goat in its mother's milk." (Deuteronomy 14:21)
The literal commandment is that we are not to eat anything that dies of itself (i.e. of natural causes).